I am not sure why Cantillon effects are not the textbook answer used to describe Spain’s emergence as a European power after contact with the New World. Simply put, as new currency goes into circulation it leads to inflation (when old currency is not removed from the market), but it does not go into an economic region uniformly. It enters via specific places and groups, and these groups then have relatively greater spending power than everyone else. They bid up prices until eventually this money circulates around and the new price level obtains throughout the market. The market participants return to their original relative levels of purchasing power.
Jack Weatherford writes in his book Indian Givers that three fifths of American bullion entering Spain went right back out as debt payments. Spain had not been a dominant country prior to contact with the Western Hemisphere, nor was it to continue in its strong position after the new money had been in circulation long enough to spread around and other powers became heavily invested in the Americas. In other words, this relative prosperity Spain briefly enjoyed did not seem to be based on any better social fundamentals than its peers had; neither the pre-contact equilibrium nor the eventual post-contact equilibrium had Spain on top of the pile.